The inventive concepts relate to a light emitting apparatus, and more particularly, to a light emitting apparatus using a light emitting device.
In recent years, high efficiency of a light emitting apparatus using a light emitting diode (hereinafter referred to as an LED) as a light emitting device is being pursued.
An LED is a semiconductor device that includes a P-type semiconductor and an N-type semiconductor bonded to each other. In the LED, electrons and holes may be combined with each other in a junction when a level of voltage is applied to the junction. The LED may emit light having a level of energy corresponding to a band gap between the P-type semiconductor and the N-type semiconductor.
An LED may be compact and lightweight, may enable generation of a lower magnitude of heat, may have a relatively long lifespan, and may have a fast response time, in comparison to an incandescent lamp. An LED may be included in one or more various types of light emitting apparatuses, including electric lights.
A light emitting apparatus using an LED generally includes an LED chip and an encapsulation layer covering and protecting the LED chip. Light emitted from the LED chip may be externally emitted from a surface of the encapsulation layer. However, because a refractive index of the encapsulation layer is greater than that of air, a relatively large portion of light emitted from the LED chip is reflected to the encapsulation layer at an interface between the encapsulation layer and the air, thereby hindering high efficiency of the light emitting apparatus.
An angle at which light emitted from an LED is received to a surface of an encapsulation layer is within a wide range. Therefore, even in a case in which only a protrusion such as a pyramid is formed on the surface of the encapsulation layer, a part or the whole of light emitted from the LED to be received to the surface of the protrusion is reflected, the reflected light returns in a direction opposite to a direction in which light is emitted by a light emitting apparatus, and is attenuated by a collision with a phosphor included in the encapsulation layer. The prior art has a problem in that light reflected from the surface of the protrusion may not be extracted as light emitted from the light emitting apparatus.
The intensity of light emitted from the LED becomes greatest in a direction in which the light is received to the surface of the encapsulation layer at an incident angle of about 45 degrees, but the prior art also has a problem in that the light received to the surface of the encapsulation layer at the incident angle may not be properly extracted as light emitted from the light emitting apparatus.